The present invention relates to a method of observing electron microscopic images and an apparatus for carrying out the same and, more particularly, to a method of observing electron microscopic images, enabling temporally-resolved observation of time-varying properties and conditions of the interior or skin layer of a specimen by passing an electron beam through the interior or the skin layer of the specimen, and an electron microscopic image observing apparatus for carrying out the method.
A prior art method of observing the time variation of the properties and conditions of the interior of a specimen by an electron microscopic image observing apparatus, such as disclosed in U.S. Pat. No. 3,628,012, transmits an intermittent electron beam through a specimen and observes the quantitative variation of actions experienced by the intermittent electron beam.
To emit an intermittent electron beam, this prior art method needs to interrupt an electron beam in the neighborhood of an electron gun provided with a high-voltage applying means of a complicated construction for accelerating electrons, requiring the interior thereof to be held in a high vacuum. An electron beam irradiation system having a high-precision construction and which is highly sensitive to electromagnetic noise is also necessary. Accordingly, the prior method needs an electron beam interrupting means comprising a deflecting coil, an aperture diaphragm and the like, which is disposed in the neighborhood of the electron gun and the electron beam irradiation system. However, the installation of the electron beam interrupting means near the electron gun and the electron beam irradiation system requires considerable modification of the apparatus and introduction of additional functions into the apparatus.
As stated above, the prior art method of observing time-resolved electron microscopic images needs an electron microscopic image observing apparatus of a construction greatly different from that of a general electron microscopic image observing apparatus which is not intended for the observation of time-resolved electron microscopic images. Thus, the prior art method cannot be carried out by a simple modification of the prevailing electron microscopic image observing apparatus.